1. Field of Invention
This invention relates to toothbrushes specifically to an improved shape of the toothbrush head and corresponding ends of the bristles.
2. Discussion of Prior Arts
Throughout history toothbrushes predominantly have been flat in shape. The main function of earlier toothbrushes was to remove superficial food particles and decrease the risk of cavities forming. The war on cavities won a major victory with the completion of a successful 1950's public water fluoridation campaign. Most major cities converted over to fluoridated water and as a result less cavities formed and people retained their teeth longer. These same teeth that were protected by the fluoridated water became subject to another silent tooth killer in gum disease. After the age of 35, gum disease became the most prevalent cause of tooth loss. In response to an increase in incidence of gum disease many tooth brushes evolved that had stiffer bristles and raised outer bristle bundle rows which stimulated the gum tissue. An example of one such toothbrush would be the Reach by Johnson and Johnson. Later toothbrush manufacturers found out that the negative effect of all this stimulation was gum recession and root surface abrasion. To this end, toothbrush manufacturers made the bristles softer with rounded and polished ends. There were ensuing complaints from users that these softer brushes lacked a certain feel that was stimulating and invigorating. Additionally, there was some clinical evidence that these softer brushes didn't rid the plaque and subsequent gum disease from the most prone areas in between the teeth. This brought about the latest barrage of tooth brushing devices.
Proxabrushes, stimudents, and a number of contoured brushes have recently made their way to the forefront to address this need to stimulate the gums between the teeth. Some of the contoured brushes such as the Crest Complete by Proctor and Gamble and Reach In Between by Johnson and Johnson are a copy of U.S. Pat. No. 3,188,673 to Newman 1964Mar. 4. These contoured brushes penetrate the interproximal (between the teeth) area better than flat brushes. There are several short comings of these contoured brushes.
The contoured brushes only contour and conform to the tooth shape in the direction of the front of the mouth to the back. It does not take into account any tooth contour in the direction from the gum line to the tooth edge or from buccal (cheek side of tooth) to lingual (tongue side of tooth). Accordingly the outer row of bristles of the contoured brushes splay or bend outward during usage. After prolonged usage the splaying becomes permanent and signifies that a toothbrush is worn out.
The pressure exerted on the dentition (tooth and gum tissue) by the outer row of bristles of this contoured brush can also damage the gum and the hard tissue. This same outer row pressure prevents the inner row from advancing and obtaining maximum penetration. This lack of penetration prevents stimulation and invigoration. It also exhibits how poorly the contour brush conforms to the tooth. Another disadvantage of the contour brush is the limited size variations to conform with different users tooth widths. The assumption is that everyone has the same width of teeth. A large man or woman may also have a small tooth width which might confuse the user as to what brush to select. Another shortfall of the contoured brush is the lack of strength of the bristles bundles in the center row. This weakens the bristles ability to clean and stimulate.
In order to obtain the needed strength for the inner bristle bundles to clean better the contour brush would have to add mass to the bristle bundles. There are three ways to add mass to bristle bundles to get better cleaning and all three have short comings. Firstly; you increase the diameter of each bristle and the bundles get bigger but more brittle, less flexible, and less able to penetrate into the deepest grooves. Less flexible, brittle bristles bundles lose their ability to sweep the food out once they have engaged it. Secondly; you increase the density or number of bristles per bundle you still will only get a certain amount of the bristles penetrating to the deepest grooves. This will result in no significant in crease in strength. Thirdly; you change the material that the bristles are made of to one that is harder and you increase the strength but lose the flexibility and gain brittlelessness. If you could increase the mass of the inner bristle bundles using one of these three examples and for the sake of argument it did increase the cleaning power, it would still be cost prohibitive to manufacture a brush using different materials and parameters for different bristle bundle locations, these facts conclude that the contoured brush design is inadequate for any future strength enhancing modifications.
The bristle bundles of the outer row are conversely too strong and their positioning brings them into contact with the gum tissue and tooth where damage does occur in the form of gum recession and abrasion. The contour bundles woefully lack the design to allow bristles to penetrate unencumbered to the deepest recesses with enough strength to clean, stimulate and protect gumline areas. This lack in design leaves the tooth more susceptible to gum disease where it most frequently starts-between the teeth. It also is responsible for gum recession and root surface abrasion in the midfacial area of the tooth. One final consequence of the design flaw is the formation of cavities in the two most susceptible spots—occlusal (biting) area and interproximally.